New filaments of polymers or copolymers having a basis of acrylonitrile and process for their manufacture



April 1 1957 R. E. F. STUCHLIK ET AL 2,788,563

NEW FI ENTS OF POLYMERS OR COPOLYMERS HAVING A BASIS OF A LONITRILEF D PROCESS FOR THEIR MANUFACTURE d. Dec

- INVENTO lPf/VE f. 5' STUCf/L/ s EORNEY NEW FILAMENTS F POLYMERS OR. COPOLY- MERS HAVING A BASIS 0F ACRYLONITRILE AND PROCESS FOR THEIR MANUFACTURE Ren Emile Fenland Stuchlik, Viileurhanne, and Jean Rosset, Lyon, France, assignors, by mesa-e assignments, to Crylor, Paris, France, a corporation of France Application December 15, 1952, Serial No. 326,134

Claims priority, application France May 17, 1952 3 Claims. (CI. 28-82) The present invention relates to the manufacture of an improved type of filaments and other extruded articles from polymers and copolymers of acrylonitrile.

It is known that polymers having a basis of acrylonitrile may be spun from solutions in solvents having a basis of dimethylformamide and that these solutions can be extruded in evaporative medium at an elevated temperature in order to obtain textile articles such as filaments, threads, artificial horse hairs, tows, films, foils and analogous materials. According to these processes the walls of the spinning chamber are heated to a temperature of at least 100 C. and sometimes as high as 400 C.

It has now been found and this is the object of the present invention, that in a process for dry spinning by starting from solutions of polymers or copolymers having a basis of acrylonitrile in a solvent having a high boiling point and in particular those having a basis of dimethylformamide one can obtain filaments and other extruded articles having a new type of structure on condition that they are extruded at a temperature at least equal to 120 and that the solution has a concentration, expressed in parts of polymer or copolymer per 100 parts of the solution which is greater than the value 15 W empn 1cally determlned where sp represents the specific viscosity of the polymer in the solvent in question determined at a concentration of 0.2% and at a temperature of 20.

Under these conditions filaments are obtained having a transverse section having an indented contour and in general having a porous structure which diminishes their density, all these characteristics being novel and according to the literature not being possessed by fibres having a basis of acrylonitrile polymers already known. It is known that the fibres having a basis of polyacrylonitrile actually known have a flattened transverse section in the form of dog bones or dumb bells (Rayon and Synthetic Textiles, 30, p. 91, April 1949) or of elliptic form (Textile Research Department American Viscose Corporation: Properties of Chemstrand Acrylic Fibre and Suggestions for Processing, March 1951, p. 2). In both these cases the surface of the filaments is perfectly smooth and without roughness.

It has furthermore most surprisingly been found that it is possible under the working conditions indicated above to extrude solutions in an evaporative atmosphere of which the temperature is lower than 100, for example in certain cases 40 or even 30, which was completely unexpected owing to the fact that one is concerned with the evaporation of solvents having a high boiling point as for example dimethylformamide which boils at 153.

The temperature at which the solution is extruded can vary within large limits and it is sometimes desirable to extrude at a temperature attaining 175 or even 200 C.

The process according to the present invention can be carried out by using either an evaporative chamber swept 2,788,563 Patented Apr. '16, 1957 by a current of air or by an arrangement similar to that described in U. S. Patent No. 2,472,842.

The production of filaments having an indented cross section is of great technical value as it is known to everybody versed in the art that such a section is very much better adapted to textile working than a fiat section or one of the dog bone type. Furthermore-the employment of evaporative chambers havinga lower temperature constitutes a very valuable feature from the economic point of view.

The annexed drawing shows a cross-section of the filament according to the present invention.

The filament is shown in the drawing as containing small irregular cellules 10 randomly distributed and formed as described herein. Certain of the cellules lie at the surface and form an indented contour for the filament.

The following examples are given to illustrate how the invention can be carried out but are not limitat-ive. The parts denote parts by weight.

Example 1 A polymer of acrylonitrile of specific viscosity 0.290 for which the minimum concentration calculated as above is is used. A composition consisting of 34.5 parts of this polymer and 65.5 parts of dimethylformamide is extruded through a spinneret of 32 holes of 0.15 mm. at a temperature of 128 C. into an evaporative chamber of which the walls are at C. and which is swept through by an air current at the same temperature produced by as piration applied to the base of the evaporative chamber.

The thread obtained has a titre of 800 decitex (720 deniers); it is stretched in the known fashion.

Filaments are obtained having the transverse section shown by the accompanying drawing in which the indented contour of the threads and the numerous alveoles are clearly shown.

The density of these filaments, determined at 20 C. by the method of floatation in an organic liquid and then measuring the density of this mixture in a pyknometer at 20 is 1.125. Their resistance to breaking is 3.5 g. per denier.

Example 2 A composition consisting of 36.9 parts of the same polymer as that described in Example 1 and 63.1 parts of dimethylformamide is heated to C. and extruded through a spinneret of 32 holes of 0.13 mm. diameter into a spinning apparatus of the type described in British Patent No. 605,579, the evaporating chamber being maintained at 55 C. and the heating chamber at 65 C.

The thread gathered up on emerging from the cell is stretched in the known manner. The transverse section of the thread resembles that of the thread obtained according to Example 1.

Example 3 A polymer of specific viscosity 0.310 is used and it is spun under the conditions described in Example 1 of copending application 221,119, filed April 4, 1951, and now abandoned, except that the concentration used is 32%. Filaments having an indented cross section analogous to those of Examples 1 and 2 are obtained.

What we claim is:

1. A synthetic filament consisting of a polymer of acrylonitrllc, said filament having in transverse section an indented contour and having a cellular structure throughout its length, the cellules containing no solid particles and having a very small cross-section in relation. to thatof the filament and being irregularly dispersed in themass of the filament.

2. A synthetic filament consisting of a polymer of acrylonitrile according to claim 1, the density of which is ."lowergthan. 1.13.

3; "A'synthetic filament consisting of a polymer of acrylonitrile according to claim 1 having a breaking strength in excess 'of 3 grams per denier.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A SYNTHETIC FILAMENT CONSISTING OF A POLYMER OF ACRYLONITRILE, SAID FILAMENT HAVING IN TRANSVERSE SECTION AN INDENTED CONTOUR AND HAVING A CELLULAR STRUCTURE THROUGHOUT ITS LENGTH, THE CELLULES CONTAINING NO SOLID PARTICLES AND HAVING A VERY SMALL CROSS-SECTION IN RELATION TO THAT OF THE FILAMENT AND BEING IRREGULARLY DISPERSED IN THE MASS OF THE FILAMENT. 